The present invention relates to a set of iron clubs and more particularly relates to a set of iron clubs in which the directivity of a golf ball, which has been hit by the iron clubs, can be stabilized.
As everybody knows, a set of iron clubs are composed of a plurality of iron clubs including long iron clubs and short iron clubs, the club numbers of which are 3 to 9, and also including a sand wedge club and a pitching wedge club.
Conventionally, the above set of iron clubs are composed as follows. A shaft of the long iron club is made long so that it can get distance. Since ball control is important in the short iron club, a loft angle of the head is gradually increased as the club number increases so that the ball can spin backward sharply.
In this connection, when an average golfer plays golf with this set of iron clubs, there is a tendency that the head is open when he hits a ball with the long iron club, so that the ball is sliced. On the contrary, there is a tendency that the face is closed when the player hits a ball with the short iron club, the shaft length of which is small, so that the ball is hooked. Especially, when the player uses the long iron club with which a ball is hit strongly so as to get distance, the swing speed is higher than that of the short iron club in which importance is attached to controlling of the ball. Therefore, when the player hits the ball with the long iron club, the head tends to open and the ball which has been hit with the long iron club tends to slice. For the above reasons, most players feels that it is difficult to hit a ball with the long iron clubs, the club numbers of which are low.
Depending upon a player, a ball is hit strongly not only with the long iron club but also the middle iron club, the club number of which is 5 to 7. Also, in this case, the swing speed is so high that the head tends to open and the ball is sliced. Accordingly, most players have a feeling that it is difficult to hit a ball with an iron club.
In order to prevent a ball from being sliced and hooked, a number of proposals have been made until now.
FIG. 5 is a view showing a main body of the head of the iron club disclosed in Japanese Unexamined Patent Publication No. 8-322969. This set of iron clubs are composed as follows. As shown in FIG. 6, as the club number is increased from the long iron club to the short iron club, inset A of the head body 1 is gradually decreased, that is, a distance from axis L of the shaft to a front end portion of the head body 1 on the heel side is gradually decreased.
When inset A of the head body 1 is increased, distance B of the center of gravity of the head body 1 is shortened, that is, a distance of a straight line from the center G of gravity of the head body 1 to shaft axis L is shortened. Accordingly, when a player hits a ball with this golf club, it becomes easy for him to close the face of the head. Therefore, when this long iron club is used, it become possible to prevent the occurrence of slice. In the short iron club, distance B of the center of gravity is extended. Therefore, it is difficult for the face of the head to be closed. Accordingly, the occurrence of hook can be prevented.
However, when the inset is gradually changed as described above, time to close the face of the head becomes different from each other for each club number. As a result, it becomes difficult for a player to hit a ball with the iron club of this set of iron clubs.